Existing vacuum systems for use in many industrial facilities, and more especially in semiconductor plants, for example, require a multiplicity of small oil-sealed vacuum pumps which are costly, and disposed to frequent maintenance problems. The prior art pumping system manifolds, when used, are often subject to pressure upsets and surges which may harm the delicate semiconductor wafers being processed since only very thin films are deposited, removed or doped.
The present system apparatus employs a central vacuum unit which is designed generously large to enable it to accept the loads, with capacity to spare, from a plurality of blower packages, one each of the packages connected to each of the separate reactors, typically low pressure chemical vapor deposition reactor chambers. The central vacuum unit communicates directly with a manifold maintained at a designated constant pre-set intermediate vacuum pressure, i.e., between the pressures at the several reactors and the central vacuum unit. At least one blower or pump, with valving, is interposed between each reactor and the common manifold, and, when discharging into the manifold, eliminates pressure surges in the manifold and reactors while yet permitting each of the reactors to operate at different pressures independently of the higher manifold designated pressure.